Despite the bold-faced names behind the scenes -- Steven Spielberg! Diablo Cody! -- it's the woman at its center that ensures "United States of Tara" is more than a gimmick with a cutesy name.

Despite the bold-faced names behind the scenes — Steven Spielberg! Diablo Cody! — it’s the woman at its center that ensures “United States of Tara” is more than a gimmick with a cutesy name. By turns oozing sexuality, vulnerability and confusion, Toni Collette gives Showtime’s latest half-hour its buoyant pulse — and a credible shot at the accolades the channel covets. Although it flirts with the preciousness that proved an irritant in the Cody-scripted “Juno,” there’s an innate sweetness at the show’s core that essentially says people become inured to all manner of strangeness in the context of family — even four disparate personalities.

In a bit of a risk, “Tara” jumps right in without pausing to explain its heroine’s backstory, taking it as a given that Collette’s suburban housewife, artist and mother, Tara, periodically closes her eyes and becomes someone else. Only in dribs and drabs during the four episodes previewed does the audience discover that she has wrestled with her condition — dissociative identity disorder (DID) — for years before choosing to go off her meds, thus inviting the “alters” back into her life. (It’s not until episode three that she finally sits down with her therapist, laying out some of the DID ground rules.)

The result, initially, is a slightly unsettling matter-of-factness about T, the flighty teenager; Buck, the surly, beer-swilling (male) homophobe; and Alice, the perfect if not exactly prim 1950s-style homemaker, dropping in unexpectedly. So the simple question “Is Mom home?” invokes an answer like, “Mom’s here, but I don’t know if Mom’s here.”

Each personality assumes a different look, but Collette impressively conveys the changes with body language as much as anything else, and one imagines there are some fabulous outtakes that will make an amusing addition to the DVD release.

Aside from Mother’s little helpers, the Gregsons are a pretty run-of-the-mill family, except for the fact that the two teenage kids — daughter Kate (Brie Larson) and son Marshall (Keir Gilchrist, who also played the nerdy lad in Fox’s “The Winner”) — both occasionally speak as if they’re working on a graduate thesis, a la “Juno.” (“I guess I should have let that fertilized egg implant itself in my uterus,” sneers Kate after Mom discovers she’s using birth control.)

Fortunately, John Corbett fares better as Tara’s patient husband, resisting a “Lolita moment” with teenage T, even though she’s technically in his wife’s body, or digging through Buck’s box of porn with “him.”

As the show progresses, the stronger moments indicate that Showtime has a more durable commodity here than just the sales pitch for “Sybil: The Series.” That’s in part because the producers have done an exceptional job of casting beyond the central roles — including Rosemarie DeWitt as Tara’s hard-to-read sister — offering hope that there will be additional veins to mine once the “Alice shows up for a parent-teacher conference” novelty begins wearing thin.

Ultimately, “Tara” will probably work best for those who embrace its pleasures without nitpicking its inconsistencies, instead delighting in the opportunity to spend time a breezy half-hour with Collette on a weekly basis. Because whatever the show’s modest shortcomings, this is unabashedly a vehicle for a star who brings meaning to the notion of having personality aplenty — and then some.